Cylindrical bearing member and method of manufacturing same

ABSTRACT

A small-bored cylindrical bearing member which can enhance the maintainability for a lubricating oil therein. The member has blind grooves in a seamless cylindrical central body portion of the interior hollow cylindrical surface of the bearing member. A method of manufacturing the cylindrical bearing member having blind grooves with blocked-in end portions extending in the longitudinal direction of the cylindrical portion and spaced from the ends of the member. The grooves can be easily formed in the central body portion of the inner circumferential cylindrical surface of the central body portion with the blocked-in ends spaced from the opposite ends of the seamless bearing member.  
     The seamless member is first formed with a tapered or flared portion at one open end which is later narrowed into a round cylindrical form. Before narrowing the tapered or flared portion, the blind grooves are formed by a groove punch pushed through the open end into the central body cylindrical portion. After narrowing, the blind grooves have blocked end portions spaced from the opposite ends of the bearing in the longitudinal direction.

TECHNICAL FIELD TO WHICH THE INVENTION PERTAINS

[0001] The present invention relates to a cylindrical bearing memberhaving a hollow cylindrical bore in which a plurality of blind grooves,which provide reservoirs for a lubricating oil, were formed in anendless inner circumferential surface of a cylindrical bore in parallelto the axial direction of the cylindrical bore, and a method ofmanufacturing the bearing member. Particularly, the present inventionrelates to a bearing member having a cylindrical bore in which theseblind grooves were blocked without their ends extending to either of theopposite ends of the cylindrical bore and a method of manufacturing thebearing member in small sizes.

BACKGROUND OF THE INVENTION

[0002] A cylindrical bearing member, which is used as sliding bearingssuch as a bearing body for a rotating shaft, a bushing for a chain andthe like by inserting a shaft, a pin or the like into the cylindricalbore of the article, has been conventionally well known. As such, acylindrical bearing member is well known, which is provided with aplurality of grooves, which function as oil reservoirs for a lubricatingoil parallel to the axial direction of the cylindrical bearing member,that is grooves, on an inner circumferential surface of the cylindricalbearing member to enhance the lubricating properties between the innercircumferential surface in a cylindrical bore of the cylindrical bearingmember, which provides a bearing surface, and a shaft, or between thecylindrical bore and a pin or the like.

[0003] In this conventional cylindrical bearing member, the grooves areextended to both ends of the cylindrical bore so that they are open onboth ends of the cylindrical bore. Thus, when a shaft is inserted intothe cylindrical bore of the cylindrical bearing member to use it as abearing member while retaining a lubricating oil in the grooves, thelubricating oil flows out of open ends in the blind grooves.Accordingly, there were problems that the oil reserve efficiency is badand when this cylindrical bearing member is used for a long period oftime the lubricating properties are deteriorated.

[0004] As a bearing member, which solved such a problem, a cylindricalbearing member in which end portions of the respective grooves in thelongitudinal direction of the member were blocked to form blind grooves,has been known (see Japanese Patent Publication No. 2963652)

[0005] The above-mentioned known cylindrical bearing member 21 is shownin FIG. 10. The cylindrical bearing member 21 is composed of acylindrical portion 24, in which a rectangular crude material 22 shownin FIG. 9 was wound into a cylindrical shape, that is, a plurality ofblind grooves 23 are formed by pressing, machining or rolling on asurface of the rectangular crude material 22 such as a band steel sheet,a steel sheet or the like, which provide oil reservoirs. These blindgrooves 23 are blocked on the respective both ends 23 a, 23 a in thewidth direction of the crude material such as a band steel sheet. Thenthe cylindrical bearing member 21 is wound into a cylindrical article(cylindrical portion) by a machine so that both ends of the rectangularcrude material such as the band steel sheet are opposed, and a corepunch is inserted into this cylindrical article to push it into acircular shape to manufacture a round cylindrical portion 24. In thethus manufactured cylindrical bearing member 2, a seam 25 between buttedportions in the rectangular crude material 22 form a groove portion.

[0006] Further, since the cylindrical bearing member 21 is formed bywinding, it is a comparatively thin member. However, as anothercylindrical bearing member comprising a thick cylindrical portion, acylindrical bearing member may be used in which blind grooves for oilreservoirs were previously formed on an inner surface, that is an innercircumferential surface (bearing surface) of a cylindrical portion witha thick wall, whose outer surface was forged to a round by undercutting,broaching or the like.

[0007] Japanese Patent Publication No. 2963652 also discloses aconventional cylindrical bearing member which is formed by winding arectangular crude material so that the ends of the rectangular crudematerial are in a butted state. Thus, there is a problem that thisbutted portion forms a seam in the width direction of the cylindricalportion. This seam provides a groove portion having no bottom. Thusthere is a problem that when this cylindrical bearing member is usedwhile inserting a shaft, a pin or the like into this cylindrical bearingmember, lubricating oil in the blind grooves leaks on the side of thegroove portion formed by the seam and flows out of the ends in thelongitudinal direction of the seam for a very short time whereby thelubricating oil cannot be held for a long period of time and thelubricating properties cannot be maintained.

[0008] Further, there is a problem that since the cylindrical portion ofthis cylindrical bearing member is formed by winding a rectangular crudematerial, manufacturing of a cylindrical portion having a thick wall isdifficult and a thick cylindrical portion cannot be formed.

[0009] Further, since in the above-mentioned conventional cylindricalbearing member comprising a cylindrical portion having a thick wall, andthe blind grooves are formed on the inner circumferential surface of thecylindrical portion by undercutting, broaching or the like, the blindgrooves cannot be formed by every one blind groove only, whereby theformation efficiency of the blind grooves are bad, a long time for itsprocessing is needed and the mass production is not suitable, whichleads to disadvantageous costs.

SUMMARY OF THE INVENTION

[0010] Accordingly, the objects of the present invention are to solvethe above-mentioned related art problems and to provide a smallcylindrical bearing member, in which maintainability for lubricating oilfilled in the blind grooves and oil reserving efficiency can be enhancedby use of seamless cylindrical portion of a cylindrical bearing memberand a thin and a relatively thick cylindrical portions can be used, aswell as to provide a method of manufacturing a cylindrical bearingmember in which blind grooves with blocked-in ends in the longitudinaldirection of the cylindrical portion can be efficiently formed on theinner circumferential surfaces thereof.

[0011] The present invention has solved said problems based on theconcepts that the circumferential portion of a cylindrical bearingmember is made seamless and that ends of each blind groove for an oilreservoir in the longitudinal direction are blocked to suppress the oilflow out of the groove. The method of manufacturing the cylindricalbearing member has solved said problems based on the conception offorming blind grooves in which both ends of each blind groove in thelongitudinal direction of the cylindrical bearing member were blocked byforming the blind grooves in a forging step with a groove punch. Herethe blind groove blocked at both ends in the longitudinal direction ofthe cylindrical bearing member means a blind groove both ends of whichare spaced away from the open ends of the cylindrical portion of thebearing member.

[0012] The bearing member of the present invention has a configurationof a cylindrical bearing member characterized in that a plurality ofblind grooves, each having blocked end portions in the longitudinaldirection, are formed in the inner circumferential surface of a seamlesscylindrical portion in parallel with the axial direction of thecylindrical portion and that said blind grooves are forged, e.g., by agroove punch in a forging step.

[0013] The bearing embodying the present invention has a configurationof a hollow cylindrical body portion with one end metal-worked from anoutwardly tapered or flared condition into a round cylindrical portion.The interior of the central body portion of the bearing has blindgrooves, preferably forged while the one end is in tapered or flaredcondition by a groove punch pushed into the hollow interior of thecentral body portion from the open tapered or flared end. Afterrestoration of the one end to the round cylindrical condition, the blindgrooves are positioned within the central body portion and have blockedends spaced inwardly from the open ends of the cylindrical bearingmember.

[0014] The method of the present invention comprises a method ofmanufacturing a cylindrical bearing member characterized by the stepsof: extruding a cylindrical column-shaped forging crude material havingrequired length to form a primary intermediate forged article whileleaving a bottom, press-fitting said primary intermediate forged articleinto a die whose one end was formed in a tapered manner with a taperedor flared punch to form a secondary intermediate forged article having atapered portion which was opened at one end of the cylindrical portionin a tapered or flared manner, pushing down a grooved punch from anopened end side into the inner portion of an endless cylindrical portionof said secondary intermediate forged article to form a tertiaryintermediate article in which a plurality of blind grooves were formedin the inner circumferential surface of the article, press-fitting saidtertiary intermediate forged article into a die whose innercircumferential surface is circular to form a fourth intermediate forgedarticle processed in a round shape with said tapered or flared portionnarrowed, and punching the bottom portion of said fourth intermediateforged article to form a plurality of blind grooves each having blockedends in the longitudinal direction of the article, in parallel to theaxial direction of the cylindrical portion.

[0015] According to one feature of the present invention, a plurality ofblind grooves, each blocked-in end portions in the longitudinaldirection, are formed in the inner circumferential surface of an endlesscylindrical portion in parallel with the axial direction of thecylindrical portion. Thus, in a case where the cylindrical bearingmember was used as a sliding bearing by inserting a shaft, a pin or thelike into the cylindrical portion of the member, a lubricating oilreserved in blind grooves is not caused to flow out of ends of thecylindrical portion by its use for a long period of time wherebyexcellent lubricating properties are maintained. Further, since theblind grooves are formed with a groove punch in a forging step, theblind grooves can be efficiently formed.

[0016] According to another feature of the present invention, beforedecreasing the diameter of a tapered portion opened at an end of thecylindrical portion to process it to a round cylindrical portion, theblind grooves are formed with the groove punch pushed from an open endside of the tapered or flared portion into the cylindrical portion.Thus, the blind grooves having blocked-in ends in a seamless cylindricalportion in the axial direction, can be efficiently formed on the innercircumferential surface of the seamless cylindrical portion.

[0017] According to another aspect of the present invention, afterforming a cylindrical primary intermediate forged article to a secondaryintermediate forged article, a tapered or flared portion in which oneend of the article is opened in a tapered or flared manner, a pluralityof grooves are formed on the inner circumferential surface of thesecondary intermediate forged article by pushing a groove punch into thesurface to make a tertiary intermediate forged article. Then thistertiary intermediate forged article is press-fitted into a die having around inner circumferential surface to make a round fourth intermediateforged article with a narrowed tapered or flared portion. As a result acylindrical bearing member having blind grooves blocked-in at both endsof the cylindrical portion respectively, can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a perspective view of a cylindrical bearing member 1showing an example of the present invention.

[0019]FIG. 2 is a front view of a cylindrical column-shaped startingmaterial showing an example of the present invention.

[0020]FIG. 3 is a front view of the starting material of FIG. 2 with amodified end portion.

[0021]FIG. 4 is an explanatory view showing the modified startingmaterial being forged in accordance with the present invention.

[0022]FIG. 5 is an explanatory view showing the working of one end ofthe material to form a tapered or flared end portion.

[0023]FIG. 6 is an explanatory view showing the formation of blindgrooves in the central body portion in accordance with the presentinvention.

[0024]FIG. 7 is an explanatory view of working the flared end portion toa round shape in accordance with the present invention.

[0025]FIG. 8 is an explanatory view showing punching the bottom portionat the end opposite to the flared end in accordance with the presentinvention.

[0026]FIG. 9 is a perspective view of a rectangular crude materialbefore winding, showing a prior art example prior to being wound into acylinder.

[0027]FIG. 10 is a perspective view of a cylindrical bearing membershowing the completed prior art example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A cylindrical bearing member made in accordance with the presentinvention is illustrated in FIGS. 1 and 8. The bearing member 1 is ahollow cylinder 2 having an inner circumferential surface 3. Theinterior surface 3 is provided with a plurality of blind grooves 4parallel to the axial direction of the hollow cylindrical portion 2. Asshown in FIG. 8, the blind grooves 4 are formed in the central portion 3c of the inner cylindrical surface of the cylindrical portion 2. Theopposite ends of the central body portion 3 c are spaced from the openends of the bearing member 1 to form top portion 3 a and bottom portion3 b. The blind grooves 4 are confined to the central body portion 3 cand terminate in blocked ends 4 a and 4 b which are spaced inwardly fromthe open ends of the cylindrical member 1 so that the end portions 3 aand 3 b of the inner cylindrical surface are provided with a continuousuninterrupted surface. The spacing from the open ends is preferablygreater than the thickness of the hollow cylindrical wall of bearingmember, so as to provide an effective barrier against leakage oflubricant out of the bearing member beyond the blocked ends of thegrooves. The cylindrical bearing member is seamless as shown in FIGS. 1and 8.

[0029] In accordance with the present invention, the cylindrical bearingmember is formed in a series of metal-working steps with the blindgrooves being formed by a groove punch in a forging step.

[0030] In the first step, a bar-shaped block of metallic startingmaterial, for example a high carbon chromium steel bar-shaped startingmaterial, was cut to the required length in accordance with the lengthof a bearing member to be manufactured. The starting material is in theform of a solid cylindrical column-shaped component 5. One end of thestarting block is modified to the form shown at 6 in FIG. 3 forinsertion into a forming die 7 shown in FIG. 4. The end-modifiedstarting block is then extruded with a die 7 and an extruding punch 8 toform a hollow cylindrical primary intermediate shaped article 9 which isopen at the top end and is closed at the bottom end by a bottom wall 9a. Preferably, the intermediate article 9 is shaped by the plastic flowof the metallic material.

[0031] A method of manufacturing the cylindrical bearing member 1 willbe described. First, a bar-shaped metallic crude material, for example ahigh-carbon chromium steel bar-shaped crude material was cut to therequired length in accordance with the size of a bearing member to bemanufactured to form cylindrical column-shaped forging materials. InFIG. 2 only one cylindrical column-shaped forging component 5 is shown.Then an end surface of this cylindrical column-shaped forging component5 was modified to form an end-surface-corrected cylindricalcolumn-shaped forging component 6 shown in FIG. 3.

[0032] Then, as shown in FIG. 4, the cylindrical column-shaped forgingcomponent 6 was cold extruded with a die 7 and a extruding punch 8 toform a cylindrical primary intermediate forged article 9 with a bottomportion 9 a by the plastic flow of the metallic material. Theend-surface modification of the component 6 facilitates the insertion ofthe component into the die 7.

[0033] Then, as shown in FIG. 5, the cylindrical primary intermediateshaped article 9 was press-fitted into a die 10 whose one end was formedin a tapered or flared shape, with a tapered or flared punch 11 to forma secondary intermediate forged article 12 having a tapered or flaredportion 12 b so that one end portion the cylindrical portion 12 a isopened or diverged in a tapered or flared manner. It should be notedthat the portion 12 b is limited to the upper end portion of the article12 and does not extend into the central body portion 12 b of the article12.

[0034] Then, as shown in FIG. 6, a groove punch 13 having convexportions 13 a was pushed into the cylindrical portion 12 a from an openside through the tapered or flared portion 12 b in the secondaryintermediate forged article 12 with the secondary intermediate forgedarticle 12 held into the die 10, so that a tertiary intermediate forgedarticle 14 with a plurality of blind grooves 4, parallel with the axialdirection of the article and formed on the entire inner circumferencesurface thereof, was formed. In this case, the leading ends of the blindgrooves 4 are blocked by pushing the groove punch 13 to a lower end ofthe cylindrical portion 12 a of the secondary intermediate forgedarticle 12 so that the blind grooves are not penetrated.

[0035] Then, the tertiary intermediate forged article 14 having blindgrooves 4 in the cylindrical portion 12 a and the tapered or flaredportion 12 b was press-fitted into a die 15 having a round innercircumferential surface with a pushing punch (not shown), as shown inFIG. 7 to narrow the tapered or flared portion 12 b in a round shape andform a cylindrical fourth intermediate forged article 16, the outershape of which has become round. As mentioned above the fourthintermediate forged article 16, which was formed in a round shape, hasblind grooves 4 on the inner circumferential surface of the cylindricalportion 12 a with the end portions of the grooves blocked.

[0036] Finally, in the cylindrical fourth intermediate forged article 16in which the blind grooves were formed in the above-mentioned forgingstep, the bottom wall 9 a on the bottom portion side of the article 16was punched out so that an open-ended cylindrical bearing member 1having blind grooves 4 with both ends blocked at 4 a and 4 b iscompleted.

[0037] Since in the cylindrical bearing member 1 manufactured in theabove-mentioned steps the cylindrical portion 2 has no seam and bothends of the blind grooves formed on the inner circumferential surfaceare blocked in the longitudinal direction of the member, in a case wherethe cylindrical bearing member was used as a sliding bearing byinserting a shaft, a pin or the like into the cylindrical portion of themember, a lubricating oil reserved in blind grooves is not caused toflow out of ends of the cylindrical portion by its use for a long periodof time whereby excellent lubricating properties can be maintained. Themethod of the present invention is particularly adapted to themanufacture of small-size bearings whose internal bore is less than 50mm. It has proved particularly suited to making roller chain bearingswhose internal bores are in the range of 5 mm. to 30 mm. A popular sizeis 6 mm.

[0038] Further, according to the above-mentioned manufacturing method,when the blind grooves 4 are formed on the inner circumferential surface3 of the cylindrical portion 2 in the cylindrical bearing member 1, theseamless cylindrical primary intermediate forged article is formed intothe secondary intermediate forged article having an one-end-opened,tapered or flared portion is formed and a plurality of blind grooves areformed on the inner circumferential surface by pushing a groove punch,and then the tapered or flared portion is narrowed to form in a roundshape. Accordingly, blind grooves blocked at both ends in thelongitudinal direction of the cylindrical portion 2 can be efficientlyformed on the inner circumferential surface 3 of the seamlesscylindrical portion 2 whereby the cylindrical bearing member 1 can beeasily manufactured.

[0039] According to the present invention, in the cylindrical bearingmember, a plurality of blind grooves, each having blocked end portionsin the longitudinal direction, are formed in the inner circumferentialsurface of a seamless cylindrical portion in parallel with the axialdirection of the cylindrical portion. Thus, in a case where thecylindrical bearing member was used as a sliding bearing by inserting ashaft, a pin or the like into the cylindrical portion of the member, alubricating oil reserved in blind grooves is not caused to flow out ofends of the cylindrical portion by its use for a long period of timewhereby excellent lubricating properties can be maintained. Further,since the blind grooves are formed with a groove punch in a forgingstep, the blind grooves can be efficiently formed, and the manufacturingof the cylindrical bearing member having blind grooves can be easilyperformed.

[0040] According to the present invention, before decreasing thediameter of a tapered or flared portion open at an end of thecylindrical portion to process it to a round cylindrical portion, theblind grooves are formed with the groove punch pushed through an openend of the tapered or flared portion into the cylindrical body portion.Thus, the blind grooves, blocked-in the ends of a seamless cylindricalportion in the axial direction, can be efficiently formed on the innercircumferential surface of the seamless cylindrical portion, and themanufacturing of the cylindrical bearing member having such blindgrooves can be easily performed.

[0041] According to the present invention, the method of the presentinvention comprises the steps of extruding a cylindrical column-shapedmember having the required length to form a primary intermediate forgedarticle while leaving a bottom wall, press-fitting said primaryintermediate forged article into a die whose one end was formed in atapered or flared manner with a tapered or flared punch to form asecondary intermediate forged article having a tapered or flared portionopen at one end of the cylindrical body portion in a tapered or flaredmanner, and pushing down a grooved punch through the open side into thecenter body portion of a seamless secondary intermediate forged articleto form a tertiary intermediate article in which a plurality of blindgrooves were formed in the inner circumferential surface of the articleat the center body portion. Thus, in the forging step a number of blindgrooves can be efficiently formed on the entire inner circumferentialsurface of the cylindrical body portion. Further, since the cylindricalportion can be formed in the forging step, thin or thick wallcylindrical portion can be properly formed.

[0042] Further, the method of the present invention includes the stepsof press-fitting said tertiary intermediate forged article, in which anumber of blind grooves were formed on the inner circumferential surfaceof the cylindrical portion except for the tapered or flared portion inthe forging step, into a die whose inner circumferential surface iscircular to form a fourth intermediate forged article processed in around shape with said tapered or flared portion narrowed, and punchingthe bottom wall of said fourth intermediate forged article. Thus thehollow cylindrical bearing member having a plurality of blind grooves,blocked at both ends of the seamless cylindrical body portion, in thelongitudinal direction of the article, can be efficiently, easilymanufactured.

1. A hollow cylindrical bearing member having an interior cylindricalsurface with a plurality of blind grooves in the central body portion ofsaid surface, each groove having blocked end portions spaced from theopposite ends of said surface in the longitudinal direction of thecylindrical surface, in parallel with the axial direction of thecylindrical surface, said blind grooves characterized by being forged bya groove punch in a forging step.
 2. A cylindrical bearing memberaccording to claim 1, characterized in that one end of said cylindricalbearing member beyond the blocked ends of the grooves is characterizedby having been first flared outwardly and then decreased in diameterinto a round cylindrical end portion, said blind grooves beingcharacterized by having been formed with said groove punch pushed intothe central body portion from the one open end while in said tapered orflared condition.
 3. A small-bored hollow cylindrical bearing memberhaving a circumferential wall of a given thickness forming an interiorcylindrical surface with a plurality of blind grooves in the centralbody portion of said surface, each groove having blocked end portionsspaced from the opposite ends of said surface in the longitudinaldirection of the cylindrical surface, said longitudinal spacing beinggreater than said given thickness, said blind grooves being in parallelwith the axial direction of the cylindrical surface, and characterizedby having been forged by a groove punch in a forging step.
 4. Acylindrical bearing member according to claim 3, wherein saidcircumferential wall forms a bore less than 50 mm. in diameter.
 5. Acylindrical bearing member according to claim 4 wherein said bore is inthe range of 5 to 30 mm.
 6. A cylindrical bearing member according toclaim 5 wherein said bore is about 6 mm.
 7. A method of manufacturing acylindrical bearing member of a given length comprising the steps of:extruding a cylindrical column-shaped metallic member having said givenlength to form a primary intermediate article having a hollowcylindrical body portion and a transverse bottom wall, press-fittingsaid primary intermediate article into a die having one end flared by aflared punch to form a secondary intermediate article having a flaredend portion open at one end of the cylindrical member in a flaredmanner, pushing down a grooved punch from said one open end into theinner central body portion of said secondary intermediate article toform a tertiary intermediate article having a plurality of blind groovesformed in the inner circumferential surface of central body portion ofthe article, press-fitting said tertiary intermediate article into a diewhose inner circumferential surface is circular to form a fourthintermediate forged article processed in a round shape with said flaredportion narrowed, and punching out the bottom wall of said fourthintermediate forged article to form a plurality of blind grooves eachhaving blocked ends spaced from the top and bottom ends of the articlein the longitudinal direction, parallel to the axial direction of thecylindrical body portion.
 8. A method according to claim 7 wherein saidextruding step forms a hollow cylindrical wall of a given thicknessforming a bore of less than 50 mm, and said flared end portion has anaxial length greater than said given thickness, whereby said blindgrooves terminate spaced from the top end of the article when thearticle is processed into a round shape.